Automatic firearm actuated by compressed air



May '5, 1931. B. A. REVELLI 1,803,946

' AUTOMATIC FIREARM AcTuATED BY coMPREssED AIR Filed Aug. 21. 1929 Si i ' ILV Patented May 5, 1931 UNITE sri s BETHELiABIEIi REVELLI, OF TURIN, ITALY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO METALLURGICA IBRESCIANA GIA TEMPINI, OF FIUMEG-RANDE, BRESCIA, ITALY, A

COMPANY OF ITALY AUTOMATIC FIREARIIVIV ACTUATED BY COMPRESSED AIR Application filed August 21, 1929, Serial No. $87,431, and in Italy June 6, 1929.

'f The present invention has for its object an automaticv lire-arm actuated by Vcompressed air and has lforgits aim to simplify v the construction while obtaining a regular action and a very much reduced recoil, in addition toa firing speed which can be reduced at will down toa few rounds per minute.

The fundamental idea-on which the present invention is basedconsists in that the breech is caused to act as a compression cylinder, and the obturator which is movable directlyY in the said breech acts as a piston compressor, discharge valve and admission valve for air thus allowing different pressures to be obtained during the phases of the automatic cycle of action. -In this device' several members are dispensed with,'that is to say special closing zo'devices, spring shocky absorbers retarding .means and the like, the same results being obtained as with the said special members but in a ybetter andlmore economical way.

' The accompanying drawing shows Vdia- V grammatically byf'way of example, affew forms of construction of the're-arm according to the present invention.` Y Y Figure' 1 is adiagrammatic partsection of the tire-arm according tothe invention.

Figure 2 shows the detail thereof.

' -Figures 3 and'i are diagrams of the pressure in the breech'chamber during the course respectively of the recoiland return Vof the obturator.

Figure 5-is a diagrammatic part axial section of the fire-arm provided with devices for-regulating the pressure according to the Apresent invention.

lFigure Gis va diagrammaticpart section 40 analogous to Figure V510i? another form of Av4.5 is'i"constituted by a breechl chamber l to 'is closed at the rear by a screw cap ii. In

order to secure hermetic sealing, the piston may be provided with one or more piston rings 5 of the type used in pistons of internal combustion engines.

Between the piston 3 and the cap 4 is arranged the recuperating spring '6. The percussionmeans consists of a small lever V'7A (see Figure 2)' which strikes thecap of 'the cartridge when on the' piston reaching its closing position the external arm of the v'lever strikes against a projection 8 of the breech chamber.

l The lire-arm as it has been described with reference tov Fig. l would not work well for the air' compressed by the piston in its recoil would V*produce an acceleration of the return travel, that -is to say, it would have the same effect as a strong recuperating spring vgiving rise to Van excessive firing speed and to a too violent Ablow of the pis- `ton against the barrel in its return.

It is consequently necessary to regulate the pressure of the air so that at the end of fthe recoil the compressed air-can find a discharge. In this manner the return travelV commences without too much force. On the other hand during the said return travel every opening must be closed again so that the reduction in pressure produced by the movement of the piston produces a certain braking of this latter. Finally, it is necessary that during'the *latter part of the return travel any braking action is removed in order to allow the piston to strike against the cartridge with the force `necessary vfor firing.

This can be obtained by the cycle represented in Figures 3 and 4, and can be effected in practice by providing the lire-arm described above in principle with systems of valves of which Figures 5, 6 and 7 give a few examples.

In the form of construction shown in Figure 5 the valve is constituted byv a rod 9 connected to the piston 3 and passing through a hole in the cap 4 and provided with a stuffing box 10. The rod presents two series offlongitudinaldischarge grooves 11 and 12, which allow the air to pass when they are within thehole in the cap.y

The fire-arm then acts as follows:

At the instant, of. firing7 after the re-A tardation due to the inertia, the piston commences its recoil (point A ofthe diagram Figure` The discharge port 11- is in the opening position during theA part AB of' thecurve (,Figure'3), that is` to say the air can. pass out: freely and thepressure remains normal. lVhenv the cylindrical portion of thel rod 9 commences to slide in the cap the compression chamber isv closed and the air is compressed, thus `absorbing the recoil ofthe piston.

lVhen the piston hasarrived at the-point corresponding to C (Figure 3) the air can again be discharged'through the port 12 and the `normal pressure is re-established. Dun ing thereturn travel the action will be the reverse of that above described. During the travel DG ofthe diagram (Figure 4) the valve is openand the pressureis normal; during the travelv corresponding to CB the valve is closed and there is a progressive reduction-in pressure and the travel of the pistonv is retarder. Through-out the distance corresponding toBA the-valve is open, air is admitted, and the piston is accelerated so that itA canvl str-ilethe cap of the cartridge with the necessary` force.

An improvement in the said system is effected by a supplementaryy discharge which remains open throughout-.the whole cycle -and has .-for its effect to lower throughout `the whole diagram the curves of compression and` depression thus producing an action analogous tothat described above but having a different firing speed.

This supplementary dischargeiis realized in practice by opening a window-in thegwall ofA the'breech or'4 of` the .cap and'providing it,with a regulatable,.closing'means Thus different firing. speeds maybe obtained.

According to-means provided for closing the said. supplementary discharge there couldY be two,l three four, orV more firing speeds, or even a continuous variation. of speed.

Figure 6 represents another form of construction in which in order to dispense with the rod 9 shown in figure 5, a Xed opening 13 is made in the breech chamber and a valve 14 is provided in the cap 4.

The opening 13 remains open during a certain part of the travel of the piston 3 and is subsequently closed by the piston itself during the remaining portion of the travel. On the other hand, the valve 14 only opens when it is struclrby the piston at the end of the recoil and is closed again when the piston commences its return travel.

Finally, Figure 7 represents another form in. whiclipiston rings Aare provided at the tworends ofthe piston and lin which any form of valve is replaced byffixed openings.

The piston 3 Ahas a longitudinal passage 15 open at the end and a window of elongated formV 16, and in the wall of the breech case 1 a fixed port 17 is provided. This form of construction gives the same diagramas is shown in Figuresy 3 and 4. Theopening 17 V- allows air to pass during the'first part of therecoil travel until itis closed by the body of the'piston- 3 itself. Thus the` period of compression ceases when the window 16is opposite the opening` 17 of: the breech chamber.

In thereturn: thev second cyclewill' be produced'- according tol the diagram of Figure 4.

It isobviousfthatthe form and details of construction couldbe varied as. desired without departing from the scope ofthe present invention. f

What I claim,A is: f

1. In an automatic fire-arm, aibarrel, a breech, a. compression chamber.- in said breech, amovablemember acting as obturating piston for saidbarrel and air compressn ing piston for said compression chamber,.an

. opening being provided in; the wall of said chamber inl proximity tothe reary end of said piston when it is in.l itslv foremost position 1n such a way asl to be4 closed byY said piston when it has. effecteda predetermined initial part of its recoilftravel-and avalve arranged in the rear end ofsaidcompression chamber, said valve being yopened by` the piston before this latter reaches theend of its recoil travel.

2.1n an automatic rearm, in` combination with ay barrel; a. breech, and an air compression`Y chamber-in said breech, ofa movable member acting as breech1 bolt: for said barrel andasa piston for said compression chambergand-.means forcreating in said chamber during Van;intermediatepart of the piston movement an increasing pressure during the rearward movementl and an increasing partial vacuum during thel forward movement of said movable member` and to remove saidpressure and said.V partial vacuum during the inalpartsofthe'movement `of said rmovable member.

3. In` an vautomatic firearm, incombination` Gli with a barrel, a breech, and an air'compression chamber in said breech, of a movable member acting as breech bolt for said barrel and as a piston for said compression chamber, and means for placing said compression chamber in connection with the exterior before said movable member has reached the end of its rearward and forward movement respectively.

In testimony that I claim the foregoing as my invention, I have signed my name.

BETHEL ABIEL REVELLI. 

